148. US became most powerful economy in large part by attracting highly educated intelligent immigrants.

Native US entrepreneurship, a highly developed American innovation, requires a high degree of intelligence. But the next tier down, the top level managers and scientists and engineers, draw heavily from highly educated intelligent immigrants in great disproportion compared to the general population.

Without them, the US would be an ordinary major power, not dominant.

Of course there are many other factors like an abundance of natural resources and being shielded by two oceans, but Brazil has those but is not even a major power, yet.